Angela E Thomas1, Susan F Baird2, Julia Anderson3. 1. Department of Haematology, Royal Hospital for Sick Children, Edinburgh EH9 1LF, UK angela.thomas2@nhs.net. 2. Department of Haematology, Royal Hospital for Sick Children, Edinburgh EH9 1LF, UK. 3. Department of Haematology, Edinburgh Royal Infirmary, Edinburgh, UK.